The present Invention relates to power tool motors and, more particularly, to a retainer which maintains the armature shaft positioned within the stator assembly of the motor.
In manufacturing electric motors, it is important to have proper alignment between the armature, which includes the rotor and commutator, with the brushes and stator assembly. Proper alignment prohibits axial movement or end play which may occur In the motor when the armature shaft is positioned within the motor. Excessive axial shifting is known to cause noise, vibration, and excessive wear during operation. Thus, it is desirable to limit axial movement of the armature shaft in the motor.
In the past, the armature shaft has induded a groove with slip rings, such as C-rings, as well as washers to maintain the axial integrity of the shaft. However, these types of connections have enables more axial play than is desired in the shaft. Thus, it would be desirable to maintain the axial integrity of the armature shaft within the motor. Also, it would be desirable to provide a registration point so that the commutator and rotor could be positioned along the shaft.
Accordingly, it is an object of the present invention to provide a retainer for an armature shaft which maintains the axial integrity of the shaft within the stator assembly of the motor. Also, the present invention provides the art with a retainer which is maintained within a bearing. The retainer and bearing are flush with the end of the armature shaft to provide registration for the armature shaft components. The present invention also provides the art with an inexpensive and efficient device to maintain the armature shaft within the stator assembly.
In accordance with a first aspect of the invention, an armature shaft comprises a shaft which has two ends. A commutator is positioned on the shaft. At least one bearing is on the shaft and is adjacent one of the ends of the shaft. The bearing has a central bore sized to balance the shaft during rotation. The central bore also has an enlarged diameter portion. A retainer is positioned on the shaft to retain the bearing on the shaft. The retainer is positioned within the enlarged bore portion of the bearing. A bearing housing surrounds the bearing and is adapted to fix with an end plate of the motor. The bearing housing has a receiving bore to receive the bearing. The bearing housing has a stepped configuration. The bearing likewise has an outer configuration which is stepped to fit within the housing. The bearing and retaining member are flush with the end of the shaft. Also, the enlarged bore portion defines an abutting shoulder which abuts against an end of the retainer.
In accordance with a second embodiment of the invention, an electric motor comprises a stator assembly with an armature rotatable within the stator assembly. A commutator is rotatable with the armature and is connected to the armature via a shaft. Brushes are associated with the commutator and the brushes are held on an end plate of the motor. At least one bearing is on the shaft and is adjacent one of the ends of the shaft. The bearing has a central bore sized to balance the shaft during rotation. The central bore also has an enlarged diameter portion. A retainer is positioned on the shaft to retain the bearing on the shaft. The retainer is positioned within the enlarged bore portion of the bearing. A bearing housing surrounds the bearing and is fixed to the end plate of the motor. The bearing housing has a receiving bore to receive the bearing. The bearing housing has a stepped configuration. The bearing likewise has an outer configuration which is stepped to fit within the bearing housing. The bearing and retaining member are flush with the end of the shaft. Also, the enlarged bore portion defines an abutting shoulder which shoulder abuts against the retainer. A second bearing is at the other end of the shaft.
In accordance with a third embodiment of the present invention, a power tool comprises a housing. A motor Is positioned within the housing. The motor includes a stator assembly with an armature rotatable within the stator assembly. A commutator is rotatable with the armature and is connected to the armature via a shaft. Brushes are associated with the commutator and the brushes are held on an end plate of the motor. At least one bearing is on the shaft and is adjacent one of the ends of the shaft. The bearing has a central bore sized to balance the shaft during rotation. The central bore also has an enlarged diameter portion. A retainer Is positioned on the shaft to retain the bearing on the shaft. The retainer is positioned within the enlarged bore portion of the bearing. A bearing housing surrounds the bearing and is fixed to the end plate of the motor. The bearing housing has a receiving bore to receive the bearing. The bearing housing has a stepped configuration. The bearing, likewise, has an outer configuration which is stepped to fit within the bearing housing. The bearing and retaining member are flush with the end of the shaft. Also, the enlarged bore portion defines an abutting shoulder which shoulder abuts against the retainer. Also, a power source is electrically coupled with the motor. An activation member is electrically coupled with the motor and the power source to energize and de-energize the motor. An output is coupled with the motor to drive a tool.